[JAVA] Cool thing about iterating a map with iterator., Java

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//'main' method must be in a class 'Rextester'.
//Compiler version 1.8.0_111

import java.util.*;
import java.lang.*;

class Rextester {  
    
//   The set supports element removal, which removes the corresponding mapping from the map, 
//   via the Iterator.remove(), Set.remove(), removeAll(), retainAll(), and clear() operations, 
//   BUT --> It does not support the add() or addAll() operations.   
//           ---> and that makes sense as you can only add "key" in here there is no key-Valu in the set
    
//   BUT ---> WHAT ABOUT THE     entySet().... hmmm      ---> MOST PROBABLY ITS NOT

public static void main(String args[])
    {
        HashMap<String, Integer> priceMap = new HashMap<>();
        
        priceMap.put("car", 1394870); // in $'s yup
        priceMap.put("vacation", 2938793);
        priceMap.put("buisness", 2387894);
        priceMap.put("experience",92840478 );
        priceMap.put("gadgets", 1472933443);
        
        
        
        Set<String> keySet = priceMap.keySet();        // Iterating using keySet() method of HashMap
        
       
        for(String key: keySet){                        // Iterating using foreach loop
           Integer value = priceMap.get(key);
           System.out.printf("key: %s, -----  value: %d %n", key, value);
        }
        System.out.println("\n\n\n\n");
        
        
        //----- Trying to change the map enteries via iterator, or the set we got ------
        
        
        // removing an elements mapping from the priceMap using iterator & keySet (a set we got)
        
        keySet.remove("car"); // REMOVED CAR 
        
        Iterator<String> itr = keySet.iterator();
        while(itr.hasNext()){
            
            String key = itr.next();
            int price = priceMap.get(key).intValue();
            
            if(key.equals("gadgets")){
                itr.remove(); // doesn't take an argument
                System.out.println("key : " + key  + "  ===   price : " + price + "\t\t** REMVED **" );
            }
            else
                System.out.println("key : " + key  + "  ===   price : " + price );
        }
        
        
        
        
        // final keySet -> overrides toString()
        System.out.println("\n\n\nfinal keySet : " + keySet);
        
        // final MAP -> overrides toString()
        System.out.println("\n\n\nfinal map (priceMap) : \n" + priceMap + "\t<<-- see all the changes are preserved");
        
        
        
        //   BUT --> It does not support the add() or addAll() operations.
        
        keySet.add("anything");
//        Exception in thread "main" java.lang.UnsupportedOperationException  <<--------

}
}

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Compilation time: 1.56 sec, absolute running time: 0.31 sec, cpu time: 0.25 sec, memory peak: 18 Mb, absolute service time: 1,88 sec